// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_SELFADJOINTRANK2UPTADE_H
#define EIGEN_SELFADJOINTRANK2UPTADE_H

namespace Eigen {

namespace internal {

    /* Optimized selfadjoint matrix += alpha * uv' + conj(alpha)*vu'
 * It corresponds to the Level2 syr2 BLAS routine
 */

    template <typename Scalar, typename Index, typename UType, typename VType, int UpLo> struct selfadjoint_rank2_update_selector;

    template <typename Scalar, typename Index, typename UType, typename VType> struct selfadjoint_rank2_update_selector<Scalar, Index, UType, VType, Lower>
    {
        static EIGEN_DEVICE_FUNC void run(Scalar* mat, Index stride, const UType& u, const VType& v, const Scalar& alpha)
        {
            const Index size = u.size();
            for (Index i = 0; i < size; ++i)
            {
                Map<Matrix<Scalar, Dynamic, 1>>(mat + stride * i + i, size - i) +=
                    (numext::conj(alpha) * numext::conj(u.coeff(i))) * v.tail(size - i) + (alpha * numext::conj(v.coeff(i))) * u.tail(size - i);
            }
        }
    };

    template <typename Scalar, typename Index, typename UType, typename VType> struct selfadjoint_rank2_update_selector<Scalar, Index, UType, VType, Upper>
    {
        static void run(Scalar* mat, Index stride, const UType& u, const VType& v, const Scalar& alpha)
        {
            const Index size = u.size();
            for (Index i = 0; i < size; ++i)
                Map<Matrix<Scalar, Dynamic, 1>>(mat + stride * i, i + 1) +=
                    (numext::conj(alpha) * numext::conj(u.coeff(i))) * v.head(i + 1) + (alpha * numext::conj(v.coeff(i))) * u.head(i + 1);
        }
    };

    template <bool Cond, typename T> struct conj_expr_if : conditional<!Cond, const T&, CwiseUnaryOp<scalar_conjugate_op<typename traits<T>::Scalar>, T>>
    {
    };

}  // end namespace internal

template <typename MatrixType, unsigned int UpLo>
template <typename DerivedU, typename DerivedV>
EIGEN_DEVICE_FUNC SelfAdjointView<MatrixType, UpLo>&
SelfAdjointView<MatrixType, UpLo>::rankUpdate(const MatrixBase<DerivedU>& u, const MatrixBase<DerivedV>& v, const Scalar& alpha)
{
    typedef internal::blas_traits<DerivedU> UBlasTraits;
    typedef typename UBlasTraits::DirectLinearAccessType ActualUType;
    typedef typename internal::remove_all<ActualUType>::type _ActualUType;
    typename internal::add_const_on_value_type<ActualUType>::type actualU = UBlasTraits::extract(u.derived());

    typedef internal::blas_traits<DerivedV> VBlasTraits;
    typedef typename VBlasTraits::DirectLinearAccessType ActualVType;
    typedef typename internal::remove_all<ActualVType>::type _ActualVType;
    typename internal::add_const_on_value_type<ActualVType>::type actualV = VBlasTraits::extract(v.derived());

    // If MatrixType is row major, then we use the routine for lower triangular in the upper triangular case and
    // vice versa, and take the complex conjugate of all coefficients and vector entries.

    enum
    {
        IsRowMajor = (internal::traits<MatrixType>::Flags & RowMajorBit) ? 1 : 0
    };
    Scalar actualAlpha = alpha * UBlasTraits::extractScalarFactor(u.derived()) * numext::conj(VBlasTraits::extractScalarFactor(v.derived()));
    if (IsRowMajor)
        actualAlpha = numext::conj(actualAlpha);

    typedef typename internal::remove_all<typename internal::conj_expr_if<int(IsRowMajor) ^ int(UBlasTraits::NeedToConjugate), _ActualUType>::type>::type UType;
    typedef typename internal::remove_all<typename internal::conj_expr_if<int(IsRowMajor) ^ int(VBlasTraits::NeedToConjugate), _ActualVType>::type>::type VType;
    internal::selfadjoint_rank2_update_selector<Scalar, Index, UType, VType, (IsRowMajor ? int(UpLo == Upper ? Lower : Upper) : UpLo)>::run(
        _expression().const_cast_derived().data(), _expression().outerStride(), UType(actualU), VType(actualV), actualAlpha);

    return *this;
}

}  // end namespace Eigen

#endif  // EIGEN_SELFADJOINTRANK2UPTADE_H
